It is known that a device using in a light emitting layer a polymer light emitting material showing light emission from the triplet excited state (hereinafter, referred to as triplet light emitting material in some cases) as a light emitting material used in a light emitting layer of a light emitting device exhibits high light emitting efficiency.
When a triplet light emitting material is used in a light emission layer, the material is occasionally used as a composition comprising a polymer compound as a matrix and a low molecular weight triplet light emitting compound. There is also a case of use as a polymer complex compound having a structure of a triplet light emitting compound at a side chain, main chain or end of the polymer. Further, there is also a case of use as a composition comprising a polymer compound as a matrix and a polymer complex compound.
As an example of the composition comprising a polymer compound as a matrix in addition to a low-molecular weight triplet light emitting compound, disclosed is a composition obtained by adding 2,8,12,17-tetraethyl-3,7,13,18-tetramethylporphyrin as a low molecular weight triplet light emitting compound to a polymer compound having a repeating unit of fluorenediyl group (APPLIED PHYSICS LETTERS, 80, 13, 2308 (2002)).
A polymer complex compound containing a structure of a triplet light emitting compound in a side chain of a polymer compound having an aromatic hydrocarbon ring in the main chain has been studied, and disclosed as its example is a compound having a structure of a low molecular weight triplet light emitting compound as described below in a side chain of a polymer compound having a fluorine structure as a repeating unit (J. Am. Chem. Soc., 2003, vol. 125, No. 3, 636-637).

A polymer complex compound containing a structure of a triplet light emitting compound in the main chain of a polymer has also been studied, and known as its example is a compound having a partial structure of tri(2-phenylpyridine)iridium complex Ir(ppy)3 as a triple light emitting compound in the main chain of a polymer having a fluorine structure as a repeating unit (JP-A No. 2003-73480).
Devices using the above-described composition and polymer complex compound in a light emitting layer, however, still do not show sufficient characteristics of the devices such as light emitting efficiency, half-life of luminance and the like.